Gelsemium

Gelsemium is an Asian and North American genus of flowering plants belonging to family Gelsemiaceae. The genus contains three species of shrubs to straggling or twining climbers. Two species are native to North America, and one to China and Southeast Asia.
Carl Linnaeus first classified G. sempervirens as Bignonia sempervirens in 1753; Antoine Laurent de Jussieu created a new genus for this species in 1789. Gelsemium is a Latinized form of the Italian word for jasmine, gelsomino. G. elegans has the common name "heartbreak grass".
Properties
All three species of this genus are poisonous.
Active components
The active components of gelsemium are the alkaloids, which are present in a concentration of about 0.5%. These consist primarily of gelsemine (a highly toxic compound related to strychnine), with lesser amounts of related compounds (gelsemicine, gelsedine, etc). Other compounds found in the plant include scopoletin (also called gelsemic acid), a small amount of volatile oil, fatty acid and tannins.
Gelsemium has been shown to contain methoxyindoles.
Medicinal uses
As late as 1906, a drug called Gelsemium, made from the rhizome and rootlets of Gelsemium sempervirens, was used in the treatment of facial and other neuralgias. It also proved valuable in some cases of malarial fever, and was occasionally used as a cardiac depressant and in spasmodic affections, but was inferior for this purpose to other remedies.
Species
Alleged poisoning victims
On 23 December 2011, Long Liyuan, a Chinese billionaire, died after eating cat stew that was allegedly poisoned with Gelsemium elegans.
On 10 November 2012, Alexander Perepilichny died outside his UK home, after warning of Kremlin death threats he received related to the Magnitsky affair. A lawyer for the deceased's life insurance company told a pre-inquest hearing that toxicology reports had identified traces of Gelsemium in his body. However, this was later denied by an expert at the Royal Botanical Gardens, Kew, the Police and coroner concluded that he died of natural causes.
Symptoms of poisoning
The poison affects the vision and respiration. Symptoms can appear almost immediately.
Arthur Conan Doyle's experiment
Sir Arthur Conan Doyle, writer of the Sherlock Holmes stories, once administered himself a small amount of gelsemium and kept increasing the amount every day until he could no longer stand the ill effects. In a letter written by him to the British Medical Journal on 20 September 1879, he described that he had persistent diarrhea, severe frontal headache, and great depression, and therefore stopped his self-experimentation at 200 minims.
A rare case of Gelsemium addiction
In his classic early 20th century work on psychotropic drugs Phantastica, German pharmacologist Louis Lewin recounts the case — seemingly unique in the literature — of an individual who became addicted (in a manner far more often associated with opiates) to a Gelsemium preparation:
during a severe attack of rheumatism a man took a large quantity of an alcoholic tincture of Gelsemium sempervirens a plant which is liable to act on the brain and the medulla oblongata. Noticing an appreciable result he continued to take it, and finally became a slave to the drug. He gradually augmented the quantity, and reached 30 gr. of the tincture in one dose. Slowly he became pale, agitated, and discontented. He wasted away. Hallucination set in, and his state grew worse until disorders of the intelligence appeared. As he continued to increase the doses he fell into idiocy and died in a state of mental confusion.
References
Further reading
This contains a detailed description of the then-common usage and dosage of the drug.
Gelsemiaceae
Gentianales genera